This invention relates generally to the field of disc drive data storage devices, and more particularly but not by way of limitation, to actuator stops for limiting the movement of the actuator in a disc drive.
Modern disc drives are commonly used in a multitude of computer environments to store large amounts of data in a form that is readily available to a user. Generally, a disc drive has a magnetic disc, or two or more stacked magnetic discs, that are rotated by a motor at a high speed. Each disc has a data storage surface divided into a series of generally concentric data tracks where data is stored in the form of magnetic flux transitions.
A data transfer member such as a magnetic transducer is moved by an actuator to selected positions adjacent the data storage surface to sense the magnetic flux transitions in reading data from the disc, and to transmit electrical signals to induce the magnetic flux transitions in writing data to the disc. The active elements of the data transfer member are supported by flex structures extending from the actuator. The active elements are maintained a small distance above the data storage surface upon an air bearing sustained by air currents caused by the spinning discs.
A continuing trend in the industry is toward ever-increasing data storage capacity and processing speed while maintaining or reducing the physical size of the disc drive. Consequently, the data transfer member and supporting structures are continually being miniaturized, while data storage densities are continually being increased. The result is an overall increased sensitivity to vibration and shock. Increased data storage capacity has also decreased the allocation of non-data storage space on the discs, resulting in minimal space for actuator landing zones. Increased processing speed also requires increased actuator acceleration and deceleration in moving the read/write head from one track to another.
These demands require fundamentally tighter control of the actuator movement so as to better control the data transfer member travel along the data storage surface. Typically, the desired limit of inward travel is the landing zone where the data transfer member is parked during disc drive shut down. Travel beyond the landing zone can cause the data transfer member to strike the motor. Conversely, the desired limit of outward travel is an overshoot cushion zone beyond the outermost data track. Travel beyond the cushion zone can cause the data transfer member to move beyond the sustaining air bearing of the spinning discs.
Actuator stops are commonly employed to limit the actuator rotational movement in order to limit the data transfer member travel. It is common to use a pair of actuator stops, an inner stop limiting inward travel and an outer stop limiting outward travel. Although there are different types of actuator stops in use, generally all are associated with an abutting engagement of the advancing actuator to positively stop the movement thereof.
It is important that the actuator stop decelerate the actuator quickly and in a short distance, but without damaging the data transfer member. For example, the impact response imparted by the actuator stop to the actuator must transfer a deceleration force that is less than a threshold force that would cause a transducer to deflect away from the flexure and thereby either contact the data storage surface or plastically deform the flexure.
Rigidly supported stop pins provide an impact response resulting in a relatively minimal stopping distance, but typically at the expense of unacceptably high deceleration forces. Cantilevered stop pins reduce the peak deceleration force but can be unpredictable, due to relatively low accuracy from warpage, and can be susceptible to imparting ringing in the actuator.
It has been found that by fashioning an actuator stop by joining a noncompliant contact member to a rigidly fixed stop pin with a compliant member therebetween, a low cost actuator stop approximating the performance of a rigid stop pin but imparting acceptable peak deceleration forces can be provided. It is this invention which is discussed hereinbelow.
In one embodiment of the present invention, an actuator stop is provided for limiting travel of a disc drive actuator. The actuator stop includes a rigid stop pin and a bumper supported by the stop pin. The bumper comprises a compliant suspension member connected to the stop pin and supporting a noncompliant contact member. The contact member has a relatively greater compressive yield strength than that of the suspension member, so that in response to an abutting engagement with the actuator, the contact member is displaceable relative to the stop pin.
Additional features and benefits will become apparent upon a review of the attached figures and the accompanying description.